Sie müssen transport_maps
in Ihrem verwendenmain.cf
#/etc/postfix/main.cf #... transport_maps = hash:/etc/postfix/transport #... #/etc/postfix/transport a@example.com smtp:smtp.a.example.com:25 b@example.com smtp:smtp.a.example.com:25 example.com smtp:smtp.b.example.com:25
transport_maps (default: empty) Optional lookup tables with mappings from recipient address to (message delivery transport, next-hop destination). See transport(5) for details. Specify zero or more "type:table" lookup tables. If you use this feature with local files, run "postmap /etc/postfix/transport" after making a change.
Ref: Postfix Docs